Re: PHP Error Messages
What version are you using? In the trunk, line 169 of bb-settings.php does not have a foreach statement, so maybe you’re using something other than the trunk release?
That error is related to not having a my-plugins folder and I think possibly not having any plugins in that folder that start with an underscore.
This was talked about a couple times:
https://bbpress.org/forums/topic/installation-problem-cannot-modify-header-information
https://bbpress.org/forums/topic/php-error-site-mangement-plugins-page
I thought the latest 0.8.3.1 release took care of that, but maybe it doesn’t.
If it were me, I would try creating a my-plugins directory, and then making sure there were some plugins in that folder.